The microbial challenge in periodontitis

Diode Laser - A Novel Therapeutic Approach in the Treatment of Chronic Periodontitis in Type 2 Diabetes Mellitus Patients: A Prospective Randomized Controlled Clinical Trial

Introduction: Maturity-onset diabetes mellitus affecting the elderly population is marked by insulin resistance and decreased insulin production. The relationship between periodontitis and diabetes is bidirectional. Type 2 diabetic patients are more prone to chronic periodontitis (CP) and severe periodontitis affects the glycemic control in such patients. Recently, dental diode laser has become an effective tool in controlling CP. To date, very few studies have been conducted to check the efficacy of diode laser in control of periodontal destruction in type 2 diabetes mellitus (DM2) patients. Hence, the need of the study was to evaluate whether diode laser helps improvement of periodontal outcome and reduction in anaerobic bacteria in elderly diabetic patients with CP. Methods: Forty DM2 patients with CP were randomized into group A (control): scaling and root planing (SRP) only and group B (test): SRP followed by soft tissue dental diode laser (808 nm) application. Four patients (2 in each group) were lost during follow up. Clinical parameters, plaque samples and glycated hemoglobin levels were evaluated at both baseline and 90 days post-treatment. Results: Improvement in clinical, microbiological and glycemic parameters were noted in the group that received SRP as well as SRP + LANAP (laser-assisted new attachment procedure). The reductions in clinical parameters were statistically significant after 3 months (P<0.001). The microbial analysis of plaque samples for Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) decreased significantly after 3 months in group B than in group A. Glycated hemoglobin level (HbA1c) decreased significantly after 90 days in both the groups (P<0.001) with more reduction in the SRP+LANAP group (6.49%) in comparison to SRP alone (16.25% vs. 9.76%). However, on the intergroup comparison, the difference in HbA1c reduction was nonsignificant. Conclusion: Laser as an adjunct to SRP is an effective procedure for improving clinical and microbiological parameters in maturity onset diabetes mellitus patients with CP. Also, there was a better improvement in glycemic control in the test group compared to control group after 3 months. Hence, medically compromised patients like DM2 with CP with delayed wound healing can effectively be treated by laser as an adjunct to nonsurgical periodontal therapy for better results.

Efficacy of using oxygen microbubble device for facultative anaerobe removal

Patients with serious gingivitis or periodontal diseases suffer from receding gums. Brushing teeth with a toothbrush may result in bleeding gums and new wounds, which increases the difficulty of removing facultative anaerobes from gum pockets, to decrease the damage inflicted on gums, this study proposed a cleaning device that can generate and emit oxygen microbubbles for eliminating facultative anaerobes in the mouth cavity. In this study, the authors conducted simulations with a denture to investigate the efficacy of using this method to remove facultative anaerobes. In this research for the optimal device design, several variables were manipulated including rotation speeds of the bubble generator, different nozzle diameters, and different numbers of nozzle holes. The results revealed that the device is effective in removing facultative anaerobes; moreover, of all design variables, the number of nozzle holes was the factor having the largest effect on anaerobe removal, as it influenced the flow volume and oxygen content of the discharge: the greater the number of nozzles, the greater the flow volume, oxygen content, and efficacy of anaerobe removal.

Identification of multiple strains of Porphyromonas gingivalis using heteroduplex polymerase chain reaction in varying severity of chronic periodontitis

Aim

Research has demonstrated that there are multiple strains of Porphyromonas gingivalis with varying potency to cause periodontal disease. The current study aims at using heteroduplex polymerase chain reaction (PCR) to detect the strain diversity of P. gingivalis in periodontitis lesions of varying severity in a sample of the Indian population.

Materials and Methods

Subgingival plaque samples were collected from 60 individuals with varying severity of chronic periodontitis and 30 individuals with a clinically healthy periodontium. The samples were subjected to PCR analysis to identify P. gingivalis, followed by heteroduplex analysis to identify the strain diversity in a given sample. Bacterial culture was carried out as a comparative standard.

Results

Of the 56 samples that were positive for P. gingivalis by PCR, 54 samples yielded eight different heteroduplex patterns. Analysis of these patterns indicated that two strains of P. gingivalis were present in 41 individuals (45.6%) and three strains were present in 13 individuals (14.4%). Detection of P. gingivalis by PCR was significantly more in the periodontitis group as compared to the healthy group.

Conclusions

Species-specific PCR and heteroduplex analysis provide a simple and accurate method to analyse the strain diversity of P. gingivalis. P. gingivalis was detected in both healthy periodontal sites as well as sites with periodontitis. The presence of two or three P. gingivalis strains was seen in 60% of the samples.

Porphyromonas gingivalis Peptidyl Arginine Deiminase Can Modulate Neutrophil Activity via Infection of Human Dental Stem Cells

Periodontitis (PD) is a widespread chronic inflammatory disease in the human population. Porphyromonas gingivalis is associated with PD and can citrullinate host proteins via P. gingivalis peptidyl arginine deiminase (PPAD). Here, we hypothesized that infection of human dental follicle stem cells (hDFSCs) with P. gingivalis and subsequent interaction with neutrophils will alter the neutrophil phenotype. To test this hypothesis, we established and analyzed a triple-culture system of neutrophils and hDFSCs primed with P. gingivalis. Mitogen-activated pathway blocking reagents were applied to gain insight into stem cell signaling after infection. Naïve hDFSCs do not influence the neutrophil phenotype. However, infection of hDFSCs with P. gingivalis prolongs the survival of neutrophils and increases their migration. These phenotypic changes depend on direct cellular contacts and PPAD expression by P. gingivalis. Active JNK and ERK pathways in primed hDFSCs are essential for the phenotypic changes in neutrophils. Collectively, our results confirm that P. gingivalis modifies hDFSCs, thereby causing an immune imbalance.

Laser reduction of specific microorganisms in the periodontal pocket using Er:YAG and Nd:YAG lasers: a randomized controlled clinical study

The objective of this study was to evaluate the microbiological and clinical outcomes following nonsurgical treatment by either scaling and root planing, combination of Nd:YAG and Er:YAG lasers, or by Er:YAG laser treatment alone. The study involved 60 patients with generalized chronic periodontitis, randomly assigned into one of three treatment groups of 20 patients. The first group received scaling and root planing by hand instruments (SRP group), the second group received Er:YAG laser treatment alone (Er group), and the third group received combined treatment with Nd:YAG and Er:YAG lasers (NdErNd group). Microbiological samples, taken from the periodontal pockets at baseline and 6 months after treatments, were assessed with PET Plus tests. The combined NdErNd laser (93.0%), followed closely by Er:YAG laser (84.9%), treatment resulted in the highest reduction of all bacteria count after 6 months, whereas SRP (46.2%) failed to reduce Treponema denticola, Peptostreptococcus micros, and Capnocytophaga gingivalis. Full-mouth plaque and bleeding on probing scores dropped after 6 months and were the lowest in both laser groups. The combination of NdErNd resulted in higher probing pocket depth reduction and gain of clinical attachment level (1.99 ± 0.23 mm) compared to SRP (0.86 ± 0.13 mm) or Er:YAG laser alone (0.93 ± 0.20 mm) in 4-6 mm-deep pockets. Within their limits, the present results provide support for the combination of Nd:YAG and Er:YAG lasers to additionally improve the microbiological and clinical outcomes of nonsurgical periodontal therapy in patients with moderate to severe chronic periodontitis.

Community Development between Porphyromonas gingivalis and Candida albicans Mediated by InlJ and Als3

The pleiomorphic yeast Candida albicans is a significant pathogen in immunocompromised individuals. In the oral cavity, C. albicans is an inhabitant of polymicrobial communities, and interspecies interactions promote hyphal formation and biofilm formation. C. albicans colonizes the subgingival area, and the frequency of colonization increases in periodontal disease. In this study, we investigated the interactions between C. albicans and the periodontal pathogen Porphyromonas gingivalisC. albicans and P. gingivalis were found to coadhere in both the planktonic and sessile phases. Loss of the internalin-family protein InlJ abrogated adhesion of P. gingivalis to C. albicans, and recombinant InlJ protein competitively inhibited interspecies binding. A mutant of C. albicans deficient in expression of major hyphal protein Als3 showed diminished binding to P. gingivalis, and InlJ interacted with Als3 heterologously expressed in Saccharomyces cerevisiae Transcriptional profiling by RNA sequencing (RNA-Seq) established that 57 genes were uniquely upregulated in an InlJ-dependent manner in P. gingivalis-C. albicans communities, with overrepresentation of those corresponding to 31 gene ontology terms, including those associated with growth and division. Of potential relevance to the disease process, C. albicans induced upregulation of components of the type IX secretion apparatus. Collectively, these findings indicate that InlJ-Als3-dependent binding facilitates interdomain community development between C. albicans and P. gingivalis and that P. gingivalis has the potential for increased virulence within such communities.IMPORTANCE Many diseases involve the concerted actions of microorganisms assembled in polymicrobial communities. Inflammatory periodontal diseases are among the most common infections of humans and result in destruction of gum tissue and, ultimately, in loss of teeth. In periodontal disease, pathogenic communities can include the fungus Candida albicans; however, the contribution of C. albicans to the synergistic virulence of the community is poorly understood. Here we characterize the interactions between C. albicans and the keystone bacterial pathogen Porphyromonas gingivalis and show that coadhesion mediated by specific proteins results in major changes in gene expression by P. gingivalis, which could serve to increase pathogenic potential. The work provides significant insights into interdomain interactions that can enhance our understanding of diseases involving a multiplicity of microbial pathogens.

Gingival crevicular fluid levels of human beta-defensin 1 in individuals with and without chronic periodontitis

BACKGROUND AND OBJECTIVE

Human beta-defensins (hBDs) contribute to innate immunity antimicrobial activity. They are also effective in the adaptive immune response and may play a crucial role in the susceptibility to diseases of the oral cavity. This study aimed to evaluate the levels of hBD-1 in the gingival crevicular fluid of individuals with and without chronic periodontitis.

MATERIAL AND METHODS

Twenty periodontally healthy individuals (H) and 20 individuals with chronic periodontitis were recruited. Gingival crevicular fluid samples were collected from: healthy sites (Hh) from periodontally healthy individuals; and healthy sites (Ph), sites with gingivitis (Pg), and sites with periodontitis (Pp) from individuals with periodontitis. The levels of hBD-1 (pg/mL) were measured using enzyme-linked immunosorbent assay. Comparisons of hBD-1 between individuals (H and chronic periodontitis) and among sites (Hh, Ph, Pg, Pp) were performed through hierarchical linear modeling.

RESULTS

Gingival crevicular fluid levels of hBD-1 were: Hh = 229.52 ± 138.96 (median 199.26), Ph = 53.88 ± 58.17 (median 35.75), Pg = 57.11 ± 40.18 (median 39.90) and Pp = 55.31 ± 37.28 (median 54.19). No influence of site diagnosis (level 1; health/gingivitis/periodontitis) was observed; however, individual diagnosis (level 2; health/periodontitis) influenced the levels of hBD-1 (P < .001).

CONCLUSION

Periodontally healthy individuals showed higher gingival crevicular fluid levels of hBD-1 when compared to individuals with chronic periodontitis. This suggests a potential protective role of hBD-1 in the susceptibility to chronic periodontitis.

Scanning Electron Microscopy Evaluation of Root Surfaces After Instrumentation With Two Piezoelectric Devices

Scanning electron microscopy evaluation of root surfaces after ultrasonic instrumentation was performed with 2 different metallic tips on piezoelectric devices. Fresh extracted teeth were collected for experimental observation and randomly divided into 2 groups: Test Group, where the root surfaces were treated using an iron, rough, double nano-structural coated (T-Black), corindone-treated tip, and Control Group where the root surfaces were treated with a conventional iron smooth tip. A scanning electronic microscope analysis was performed and the surface roughness and the amount of residual debris were evaluated. Descriptive and inferential statistics were performed. Twenty specimens were analyzed, 10 per group and a total of 21.4 × 10 μm has been observed. On treated area percentage of debris after ultrasonic scaling in Test Group was 1.9 ± 1.8%, while in Control Group it was 5.7 ± 4.3%. Within the limits of the study, it seems that the efficacy of the novel iron, rough, double nano-structural coated (T-Black), corindone-treated structure tip showed greater performance in terms of root surface debridement than the conventional iron smooth tip. The possibility to use a single tool (ultrasonic device with a specific tip) for the root planing procedure within the nonsurgical mechanical therapy may represent a significant advantage for the clinicians. The tested novel tip seems to be able to show the requested ideal characteristics. However, further clinical studies are needed to demonstrate the in vitro results.

[Effect of inflammaging on periodontitis]

Inflammaging is the chronic, systematic, and controllable upregulation of a pro-inflammation state with advancing age. Chronic low-grade inflammation accompanied by sustained stimuli is correlated with various age-related diseases (ARDs). Recent studies on ARDs have prompted further research interest in the inner mechanisms underlying inflammaging to establish prevention and treatment plans for inflammatory diseases. In this article, we discuss inflammaging and its significant role in periodontitis.

β-carotene suppresses Porphyromonas gingivalis lipopolysaccharide-mediated cytokine production in THP-1 monocytes cultured with high glucose condition

Periodontitis is associated with development of diabetes mellitus. Although lipopolysaccharide (LPS) of Porphyromonas gingivalis (Pg), a major pathogen of periodontitis, may lead the progression of diabetes complications, the precise mechanisms are unclear. We, therefore, investigated the effects of β-carotene on production of Pg LPS-induced inflammatory cytokines in human monocytes cultured high glucose (HG) condition. THP-1 cells were cultured under 5.5 mM or 25 mM glucose conditions, and cells were stimulated with Pg LPS. To investigate the productivity of TNF-α, IL-6, and MCP-1, cell supernatants were collected for ELISA. To examine the effects of NF-kB signals on cytokine production, Bay11-7082 was used. HG enhanced Pg LPS-induced production of TNF-α, IL-6, and MCP-1 via NF-kB signals in THP-1. β-carotene suppressed the enhancement of the Pg LPS-induced cytokine production in THP-1 via NF-κB inactivation. Our results suggest that β-carotene might be a potential anti-inflammatory nutrient for circulating Pg LPS-mediated cytokine production in diabetic patients with periodontitis.

The making of a miscreant: tobacco smoke and the creation of pathogen-rich biofilms

We have previously reported that oral biofilms in clinically healthy smokers are pathogen-rich, and that this enrichment occurs within 24 h of biofilm formation. The present investigation aimed to identify a mechanism by which smoking creates this altered community structure. By combining in vitro microbial–mucosal interface models of commensal (consisting of Streptococcus oralis, Streptococcus sanguis, Streptococcus mitis, Actinomyces naeslundii, Neisseria mucosa and Veillonella parvula) and pathogen-rich (comprising S.oralis, S.sanguis, S.mitis, A.naeslundii, N.mucosa and V.parvula, Fusobacterium nucleatum, Porphyromonas gingivalis, Filifactor alocis, Dialister pneumosintes, Selenonomas sputigena, Selenominas noxia, Catonella morbi, Parvimonas micra and Tannerella forsythia) communities with metatranscriptomics, targeted proteomics and fluorescent microscopy, we demonstrate that smoke exposure significantly downregulates essential metabolic functions within commensal biofilms, while significantly increasing expression of virulence genes, notably lipopolysaccharide (LPS), flagella and capsule synthesis. By contrast, in pathogen-rich biofilms several metabolic pathways were over-expressed in response to smoke exposure. Under smoke-rich conditions, epithelial cells mounted an early and amplified pro-inflammatory and oxidative stress response to these virulence-enhanced commensal biofilms, and a muted early response to pathogen-rich biofilms. Commensal biofilms also demonstrated early and widespread cell death. Similar results were observed when smoke-free epithelial cells were challenged with smoke-conditioned biofilms, but not vice versa. In conclusion, our data suggest that smoke-induced transcriptional shifts in commensal biofilms triggers a florid pro-inflammatory response, leading to early commensal death, which may preclude niche saturation by these beneficial organisms. The cytokine-rich, pro-oxidant, anaerobic environment sustains inflammophilic bacteria, and, in the absence of commensal antagonism, may promote the creation of pathogen-rich biofilms in smokers.

Tobacco smoke inhibits the metabolism of beneficial bacteria in biofilms, while activating specific genes in pathogenic bacteria. This suggests a mechanism to explain how smoking quickly leads to the formation of damaging biofilms in the mouth and respiratory tract. Purnima Kumar and colleagues at Ohio State University, USA studied the effect of tobacco smoke on cultured biofilms used to model those that form on mucous membranes. They detected specific and varied changes in the activity of genes, proteins and metabolism that allowed pathogenic bacteria to displace beneficial “commensal” bacteria. The research suggests the transition toward pathogen-rich biofilms may contribute to the health effects of smoking by causing increased inflammation of mucous membranes and the production of damaging oxidant chemicals. Further research should investigate the chemical constituents of smoke responsible for these effects.

In vitro studies of the antimicrobial effect of non-thermal plasma-activated water as a novel mouthwash

The aim of this study was to evaluate the antimicrobial effects of non-thermal plasma-activated water (PAW) as a novel mouthwash in vitro. Three representative oral pathogens - Streptococcus mutans, Actinomyces viscosus and Porphyromonas gingivalis - were treated with PAW. The inactivation effect was evaluated using the colony-forming unit (CFU) method, and the morphological and structural changes of a cell were observed by scanning electron microscopy and transmission electron microscopy (TEM). The physicochemical properties of PAW were analysed, and its influence on the leakage of intracellular proteins and DNA was evaluated. The results showed significant reduction of Streptococcus mutans within 60 s, of Actinomyces viscosus within 40 s, and of Porphyromonas gingivalis in less than 40 s. Scanning electron microscopy and TEM images showed that the normal cell morphology changed by varying degrees after treatment with PAW. Intracellular proteins (280 nm) and DNA (260 nm) leaked from all three species of bacteria after treatment with PAW. Reactive oxygen species (ROS), especially atomic oxygen (O), hydroxyl radical (˙OH), and hydrogen peroxide (H₂ O₂ ), were generated and led to strong oxidative stress and cell damage. These results suggest that PAW has potential use as a novel antimicrobial mouthwash.

Relationships between initial probing depth and changes in the clinical parameters following non-surgical periodontal treatment in chronic periodontitis

Purpose:

The aim of this study was to evaluate the relationship between initial probing depth (IPD) and changes in clinical parameters following non-surgical periodontal treatment (NPT) in chronic periodontitis patients.

Subjects and Methods:

A total of 1672 periodontal pockets having 3mm≤IPD≤9mm of depth in 15 chronic periodontitis patients were included. NPT consisting of oral hygiene instructions, scaling and root planing was applied in two sessions. Probing depth (PD), clinical attachment level, gingival recessions (GR) were measured before and eight weeks after treatment. Pocket sites were grouped according to their IPD and root number as single- or multi-rooted teeth.

Results:

Other than the sites having 3 mm IPD, PD reduction and GR increase were significant in all groups (p<0.001). Attachment gains (AG) were significant in all single-rooted teeth (p<0.001) again except those having IPD=3mm. However, AG was significant in multi-rooted teeth having only 7mm≤IPD≤9mm (p<0.05). Positive correlations were observed between IPD and PD reduction, GR increase and AG in single-rooted teeth (p<0.001). Furthermore, positive correlations were found between IPD and PD reduction and GR increase in multi-rooted teeth (p<0.001), but there was no correlation between IPD and AG.

Conclusion:

NPT may lead to positive association between IPD and PD reduction as well as GR increase, which is independent from tooth root anatomy.

The anti-bacterial activity of titanium-copper sintered alloy against Porphyromonas gingivalis in vitro

This study investigates the anti-bacterial property of Ti-Cu sintered alloys against Porphyromonas gingivalis. The anti-anaerobic property of Ti-Cu sintered alloys against P. gingivalis was investigated by antibacterial activity test, DNA measurement, DAPI staining and morphology observation. The antibacterial rates of the Ti-5Cu against P. gingivalis after 18 and 24 h incubation were 36.04 and 54.39%, and those of Ti-10Cu were 68.69 and 75.39%, which were lower than their anti-aerobic abilities. The concentration of P. gingivalis DNA gradually decreased with the increasing Cu content, which was nearly 50% after 24 h incubation on Ti-10Cu. SEM results showed that the shape of P. gingivalis changed and the bacteria broke apart with the addition of Cu and the extension of the culture time. Ti-Cu sintered alloys could not only kill anaerobic bacteria but also reduce the activity of the survived bacteria. The anti-anaerobic mechanism was thought to be in associated with the Cu ion released from Ti-Cu alloy.

A tale of two risks: smoking, diabetes and the subgingival microbiome

Although smoking and diabetes have been established as the only two risk factors for periodontitis, their individual and synergistic impacts on the periodontal microbiome are not well studied. The present investigation analyzed 2.7 million 16S sequences from 175 non-smoking normoglycemic individuals (controls), smokers, diabetics and diabetic smokers with periodontitis as well as periodontally healthy controls, smokers and diabetics to assess subgingival bacterial biodiversity and co-occurrence patterns. The microbial signatures of periodontally healthy smokers, but not diabetics, were highly aligned with the disease-associated microbiomes of their respective cohorts. Diabetics were dominated by species belonging to Fusobacterium, Parvimonas, Peptostreptococcus, Gemella, Streptococcus, Leptotrichia, Filifactor, Veillonella, TM7 and Terrahemophilus. These microbiomes exhibited significant clustering based on HbA1c levels (pre-diabetic (<6.5%), diabetic (6.5–9.9%), diabetics >10%). Smokers with periodontitis evidenced a robust core microbiome (species identified in at least 80% of individuals) dominated by anaerobes, with inter-individual differences attributable largely to the ‘rare biosphere’. Diabetics and diabetic smokers, on the other hand, were microbially heterogeneous and enriched for facultative species. In smokers, microbial co-occurrence networks were sparse and predominantly congeneric, while robust inter-generic networks were observed in diabetics and diabetic smokers. Smoking and hyperglycemia impact the subgingival microbiome in distinct ways, and when these perturbations intersect, their synergistic effect is greater than what would be expected from the sum of each effect separately. Thus, this study underscores the importance of early intervention strategies in maintaining health-compatible microbiomes in high-risk individuals, as well as the need to personalize these interventions based on the environmental perturbation.

Determining the relationship between atherosclerosis and periodontopathogenic microorganisms in chronic periodontitis patients

OBJECTIVES

The aim of this study is to determine the relationship between atherosclerosis and periodontopathogenic microorganisms in chronic periodontitis patients following periodontal treatment.

MATERIALS AND METHODS

A total of 40 patients were included in the study. 20 of these patients diagnosed with atherosclerosis and chronic periodontitis formed the test group. The remaining 20 patients were systemically healthy patients diagnosed with chronic periodontitis and formed the control group. All patients had nonsurgical periodontal treatment. The periodontopathogenic microorganism levels were determined at baseline and at 6 months in microbial dental plaque samples and WBC, LDL, HDL, PLT, fibrinogen, creatinine and hs-CRP levels were determined by blood samples.

RESULTS

Statistically significant reduction has been achieved in clinical periodontal parameters following non-surgical periodontal treatment in test and control groups. Following periodontal treatment, WBC, LDL, PLT, fibrinogen, creatinine and hs-CRP levels significantly decreased and HDL levels significantly increased in both test and control groups. Similarly, the periodontopathogenic microorganism levels significantly decreased following periodontal treatment in the test and control groups. A statistically significant positive correlation has been determined between the periodontopathogenic microorganism levels and WBC, LDL, PLT, fibrinogen, creatinine, and hs-CRP levels in the test group.

CONCLUSIONS

The association between hs-CRP, WBC, LDL, PLT, fibrinogen, creatinine, and the amount of periodontopathogenic microorganisms indicates the possibility that periodontal treatment could decrease the risk atherosclerosis. More studies must be conducted in order for these results to be supported.

Epidemiology of Oral and Maxillofacial Infections

Dental caries and periodontal disease are the most common dental infections and are constantly increasing worldwide. Distribution, occurrence of dental caries, gingivitis, periodontitis, odontogenic infections, antibiotic resistance, oral mucosal infections, and microbe-related oral cancer are important to understand the public impact and methods of controlling such disease. Distribution of human papilloma virus and human immunodeficiency virus -related oral cancers in the US population is presented.

Periodontal and peri-implant wound healing following laser therapy

Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO2 , neodymium-doped yttrium-aluminium-garnet (Nd:YAG) and diode lasers have mainly been used for periodontal soft-tissue management. With development of the erbium-doped yttrium-aluminium-garnet (Er:YAG) and erbium, chromium-doped yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft-tissue management to hard-tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri-implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti-inflammatory agents, phototherapy using lasers and light-emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low- and high-level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri-implant diseases. This article discusses the outcomes of laser therapy in soft-tissue management, periodontal nonsurgical and surgical treatment, osseous surgery and peri-implant treatment, focusing on postoperative wound healing of periodontal and peri-implant tissues, based on scientific evidence from currently available basic and clinical studies, as well as on case reports.

Biochemical and genome sequence analyses of Megasphaera sp. strain DISK18 from dental plaque of a healthy individual reveals commensal lifestyle

Much of the work in periodontal microbiology in recent years has focused on identifying and understanding periodontal pathogens. As the majority of oral microbes have not yet been isolated in pure form, it is essential to understand the phenotypic characteristics of microbes to decipher their role in oral environment. In this study, strain DISK18 was isolated from gingival sulcus and identified as a Megasphaera species. Although metagenomics studies revealed Megasphaera species as a major group within the oral habitat, they have never been isolated in cultivable form to date. Therefore, we have characterized the DISK18 strain to better understand its role in the periodontal ecosystem. Strain Megasphaera sp. DISK18 displayed the ability to adhere and self-aggregate, which are essential requisite features for inhabiting and persisting in oral cavity. It also coaggregated with other pioneer oral colonizers like Streptococcus and Lactobacillus species but not with Veillonella. This behaviour points towards its role in the ecologic succession of a multispecies biofilm as an early colonizer. The absence of virulence determining genes as observed in whole genome sequence analysis coupled with an inability to degrade collagen reveals that Megasphaera sp. strain DISK18 is likely not a pathogenic species and emphasizes its commensal lifestyle.

Effects of Specimen Collection Methodologies and Storage Conditions on the Short-Term Stability of Oral Microbiome Taxonomy

Community profiling of the oral microbiome requires the recovery of quality sequences in order to accurately describe microbial community structure and composition. Our objective was to assess the effects of specimen collection method, storage medium, and storage conditions on the relative abundance of taxa in saliva and plaque identified using 16S rRNA genes. We also assessed short-term changes in taxon composition and relative abundance and compared the salivary and dental plaque communities in children and adults. Over a 2-week period, four successive saliva and dental plaque specimens were collected from four adults with no dental decay (108 samples), and two successive specimens were collected from six children with four or more erupted teeth (48 samples). There were minimal differences in community composition at the phylum and operational taxonomic unit levels between dental plaque collection using a scaler and collection using a CytoSoft brush. Plaque samples stored in OMNIgene medium showed higher within-sample Shannon diversity, were compositionally different, and were more similar to each other than plaque stored in liquid dental transport medium. Saliva samples stored in OMNIgene recovered similar communities for at least a week following storage at room temperature. However, the microbial communities recovered from plaque and saliva stored in OMNIgene were significantly different in composition from their counterparts stored in liquid dental transport medium. Dental plaque communities collected from the same tooth type over four successive visits from the same adult did not significantly differ in structure or composition.

IMPORTANCE

Large-scale epidemiologic studies require collection over time and space, often with multiple teams collecting, storing, and processing data. Therefore, it is essential to understand how sensitive study results are to modest changes in collection and storage protocols that may occur with variation in personnel, resources available at a study site, and shipping requirements. The research presented in this paper measures the effects of multiple storage parameters and collection methodologies on the measured ecology of the oral microbiome from healthy adults and children. These results will potentially enable investigators to conduct oral microbiome studies at maximal efficiency by guiding informed administrative decisions pertaining to the necessary field or clinical work.

Biomarker levels in gingival crevicular fluid of subjects with different periodontal conditions: A cross-sectional study

OBJECTIVE

To compare five biomarker levels in gingival crevicular fluid (GCF) in different tooth-sites of subjects with healthy periodontium, aggressive periodontitis and severe chronic periodontitis, and to evaluate the value of these biomarker levels for diagnosis of the type and activity of periodontitis.

MATERIALS AND METHODS

Prior to therapy, GCF samples were collected using filter paper strip at different tooth-sites of 10 subjects with healthy periodontium (H), 15 with severe chronic periodontitis (CP) and 15 with aggressive periodontitis (AgP). The strips were weighed and the periodontal clinical parameters were recorded. Levels of interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α), C-reactive protein (CRP), and alkaline phosphatase (ALP) in GCF were assessed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The volumes of the GCF samples obtained in CP and AgP subjects were significantly higher than those from subjects with healthy periodontium (P<0.05). Levels of IL-6, TNF-α, CRP and ALP were significantly higher in the untreated disease sites in the CP and AgP groups compared to those in control sites in the H group, while IL-10 levels were lower in the CP and AgP groups than those in the control sites in the H group. However, the levels of all five biomarker levels showed significant correlation with the clinical parameters.

CONCLUSION

The measurement of five biomarker levels in GCF may facilitate overall screening of periodontitis patients in epidemiological studies and allow estimation of periodontitis activity.

The Adjunctive Use of the Erbium, Chromium: Yttrium Scandium Gallium Garnet Laser in Closed Flap Periodontal Therapy. A Retrospective Cohort Study

Objectives:

The current periodontal literature has been inconsistent in finding an added advantage to using lasers in periodontal therapy. The aim of this study was to compare treatment outcomes following root surface instrumentation alone (NL group), or with adjunctive use of Erbium, Chromium: Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser (L group).

Material and Methods:

Patients diagnosed with generalized chronic periodontitis, having a minimum of 1 year follow up were selected by a blinded party for inclusion in a retrospective analysis from patients treated prior to and after integration of laser in a single clinic setting. Probing depths (PD) of all sites ≥5 mm and full mouth bleeding scores were analyzed. Further analysis was carried out on the treatment outcomes of only the molar teeth and of pockets >6mm.

Results:

53 patients were included (25 NL,28 L). There was no significant difference between baseline PDs (NL=6.19mm, L=6.27mm, range 5-11mm). The mean PD after one year was 2.83mm (NL) 2.45mm (L), with the mean PD reductions being 3.35mm (NL) and 3.82mm (L) (p<0.002). The mean PD reduction for the molars were 3.32mm (NL) and 3.86mm (L) (p< 0.007), and for ≥7mm group were 4.75mm (NL) compared to 5.14mm (L) (p< 0.009). There was significantly less bleeding on probing in the laser group after one year (p<0.001)

Conclusion:

Both treatment modalities were effective in treating chronic periodontitis, but the added use of laser may have advantages, particularly in molar tooth sites and deeper pockets. Further research with RCTs is needed to test this hypothesis further.

Withaferin A inhibits inflammatory responses induced by Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans in macrophages

Periodontitis is a progressive chronic inflammatory disease and a major cause of tooth loss in humans. As a withanolides, withaferin A (WA) is known to exhibit strong anti‑inflammatory activity. The present study examined whether WA inhibited inflammatory responses in macrophages in response to two representative periodontal pathogens, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans. Murine bone marrow‑derived macrophages (BMDMs) were used in this study and cytokine production in culture supernatants was measured by enzyme‑linked immunosorbent assays. Western blot analysis was performed to determine the activation of nuclear factor‑κB and mitogen‑activated protein kinases (MAPKs) and the expression of inducible nitric oxide synthase (iNOS), toll‑like receptor (TLR) 2 and TLR4. The production of nitric oxide (NO) was determined by the Griess reaction. WA treatment was shown to decrease interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α production in BMDMs in response to F. nucleatum and A. actinomycetemcomitans in a dose‑dependent manner. The phosphorylation of IκB‑α and MAPKs (p38, extracellular signal‑regulated kinases and c‑Jun N‑terminal kinases) induced by F. nucleatum and A. actinomycetemcomitans was also inhibited by WA. F. nucleatum and A. actinomycetemcomitans induced iNOS expression and NO production in BMDMs, which was inhibited by WA in a dose‑dependent manner. WA also reduced endogenous and induced expression of TLR2 and TLR4 in these cells. These results suggest that WA may be a potential therapeutic agent or preventive additive for periodontitis control.

The use of systemic antibiotics in the treatment of refractory periodontitis: A systematic review

BACKGROUND

The goal in treating refractory periodontitis (RP) is to arrest or slow disease progression, which usually has included the use of systemic antibiotics adjunct to conventional mechanical debridement. The aim of this systematic review was to evaluate the evidence that the association of systemic antibiotics with conventional mechanical debridement increases the efficacy of periodontal therapy in the treatment of RP.

TYPES OF STUDIES REVIEWED

The authors searched for studies in PubMed MEDLINE, Cochrane Central Register of Controlled Trials, Thomson Reuters Web of Science, Scopus, Latin American and Caribbean Center on Health Sciences Information, and Scientific Electronic Library Online electronic databases by using selected key words from the earliest records up through October 31, 2014. Only clinical intervention studies in which investigators compared the treatment of participants with RP with either mechanical debridement alone or associated with systemic antibiotics were eligible for selection. Two authors independently assessed the risk of bias of each selected study.

RESULTS

The authors identified 13 articles and included 6 of them. Investigators in all studies reported greater reductions in probing depth or in loss of clinical attachment level after adjunct systemic antibiotic therapy when compared with mechanical debridement alone. Antibiotics tested included metronidazole, clindamycin, tetracycline hydrochloride, amoxicillin, and amoxicillin and potassium clavulanate. Five studies presented a high risk of bias, and 1 study presented an unclear risk.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The overall quality of the evidence does not allow the conclusion that adjunct systemic antibiotics are of additional benefit to conventional mechanical debridement alone.

Silicon Nitride Bioceramics Induce Chemically Driven Lysis in Porphyromonas gingivalis

Organisms of Gram-negative phylum bacteroidetes, Porphyromonas gingivalis, underwent lysis on polished surfaces of silicon nitride (Si3N4) bioceramics. The antibacterial activity of Si3N4 was mainly the result of chemically driven principles. The lytic activity, although not osmotic in nature, was related to the peculiar pH-dependent surface chemistry of Si3N4. A buffering effect via the formation of ammonium ions (NH4(+)) (and their modifications) was experimentally observed by pH microscopy. Lysis was confirmed by conventional fluorescence spectroscopy, and the bacteria's metabolism was traced with the aid of in situ Raman microprobe spectroscopy. This latter technique revealed the formation of peroxynitrite within the bacterium itself. Degradation of the bacteria's nucleic acid, drastic reduction in phenilalanine, and reduction of lipid concentration were observed due to short-term exposure (6 days) to Si3N4. Altering the surface chemistry of Si3N4 by either chemical etching or thermal oxidation influenced peroxynitrite formation and affected bacteria metabolism in different ways. Exploiting the peculiar surface chemistry of Si3N4 bioceramics could be helpful in counteracting Porphyromonas gingivalis in an alkaline pH environment.

C/EBP β Mediates Endoplasmic Reticulum Stress Regulated Inflammatory Response and Extracellular Matrix Degradation in LPS-Stimulated Human Periodontal Ligament Cells

Periodontitis is an oral inflammatory disease that not only affects the integrity of local tooth-supporting tissues but also impacts systemic health. A compositional shift in oral microbiota has been considered as the main cause of periodontitis; however, the potential mechanism has not been fully defined. Herein, we investigated the role of CCAAT/enhancer-binding protein β (C/EBP β), a member of the C/EBP family of transcription factors, in human periodontal ligament cells (hPDLCs) exposed to Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS). RT-PCR and Western blotting analysis showed that the expression of C/EBP β was significantly increased in hPDLCs stimulated with LPS stimuli. Overexpression of C/EBP β by the recombinant adenoviral vector pAd/C/EBP β markedly increased the expression of the pro-inflammatory cytokines IL-6 and IL-8, and matrix metalloproteinases (MMP)-8 and -9 in hPDLCs in response to LPS. Furthermore, the activation of endoplasmic reticulum (ER) stress was confirmed in LPS-stimulated hPDLCs by measuring the expression of the ER stress marker molecules protein kinase-like ER kinase (PERK), eIF2α, GRP78/Bip, and C/EBP homologous protein (CHOP). The ER stress inhibitor salubrinal repressed, but inducer tunicamycin enhanced, the production of IL-6, IL-8, MMP-8, and MMP-9 in hPDLCs. Additionally, ER stress inducer tunicamycin significantly increased the expression level of C/EBP β in hPDLCs. Blocking of C/EBP β by siRNA resulted in a significant decrease in the secretion of IL-6 and IL-8 and expression of MMP-8 and MMP-9 induced by tunicamycin treatment in hPDLCs. Taken together, ER stress appears to play a regulatory role in the inflammatory response and extracellular matrix (ECM) degradation in hPDLCs in response to LPS stimuli by activating C/EBP β expression. This enhances our understanding of human periodontitis pathology.

Quantification of Canine Dental Plaque Using Quantitative Light-Induced Fluorescence

The aim of this work was to evaluate Quantitative Light-induced Fluorescence (QLFTM) as an alternative to the established Logan and Boyce method for determining plaque coverage of dogs’ teeth. In a series of studies in conscious and anesthetized dogs, QLF showed good intra-photographer repeatability (coefficient of variation [CV] of 7.5% for undisclosed teeth) and inter-photographer reproducibility (CV of 3.2% for undisclosed teeth and 8.5% for disclosed teeth). The QLF software accurately identifies areas of plaque as demonstrated by comparison to the variability of 5 human scorers, manually marking plaque on QLF-acquired images ( P = 0.1). There was good agreement with the modified Logan and Boyce method in the percentage reduction in plaque accumulation measured when dogs were fed an oral care chew versus no chew. To see a 15% difference in plaque accumulation, which is considered sufficient by the Veterinary Oral Health Council to differentiate between 2 treatments, a retrospective power analysis (90%) of the data established that only 7 dogs would be required, compared to 19 dogs for the modified Logan and Boyce method. QLF is a reliable method for measuring dental plaque in dogs with the added advantage that it is not subjective and requires fewer animals.

Probiotics in the treatment of periodontal disease: A systematic review

Over the years, probiotics have been used in the treatment of a variety of diseases. The use of probiotics in the treatment of periodontal disease has caught on over the last decade or so. This review was performed to determine whether administration of probiotics produced a lasting clinical benefit in the treatment of periodontal disease. A MEDLINE, Cochrane database and a hand search was performed on human randomized placebo controlled trials using probiotics in the treatment of periodontal disease. A total of thirteen papers which addressed the question of the use of probiotics in the treatment of periodontal disease were retrieved. Most of the studies reviewed showed only a short term benefit with regards to reduction in gingival inflammation and probing depth reduction. Lasting clinical benefits were not seen in any of the studies. At least four different combinations and strains of probiotics have been used in the studies. There also existed significant heterogeneity in the methodology of the studies reviewed. It was concluded that current regimens of probiotics in the treatment of periodontal disease produce only short-term clinical and microbiologic benefits.

Malva sylvestris Inhibits Inflammatory Response in Oral Human Cells. An In Vitro Infection Model

The aim of this study was to investigate the in vitro anti-inflammatory activity of Malva sylvestris extract (MSE) and fractions in a co-culture model of cells infected by Aggregatibacter actinomycetemcomitans. In addition, we evaluated the phytochemical content in the extract and fractions of M. sylvestris and demonstrated that polyphenols were the most frequent group in all samples studied. An in vitro dual-chamber model to mimic the periodontal structure was developed using a monolayer of epithelial keratinocytes (OBA-9) and a subepithelial layer of fibroblasts (HGF-1). The invasive periodontopathogen A. actinomycetemcomitans (D7S-1) was applied to migrate through the cell layers and induce the synthesis of immune factors and cytokines in the host cells. In an attempt to analyze the antimicrobial properties of MSE and fractions, a susceptibility test was carried out. The extract (MIC 175 μg/mL, MBC 500μg/mL) and chloroform fraction (MIC 150 μg/mL, MBC 250 μg/mL) were found to have inhibitory activity. The extract and all fractions were assessed using a cytotoxicity test and results showed that concentrations under 100 μg/mL did not significantly reduce cell viability compared to the control group (p > 0.05, viability > 90%). In order to analyze the inflammatory response, transcriptional factors and cytokines were quantified in the supernatant released from the cells. The chloroform fraction was the most effective in reducing the bacterial colonization (p< 0.05) and controlling inflammatory mediators, and promoted the down-regulation of genes including IL-1beta, IL-6, IL-10, CD14, PTGS, MMP-1 and FOS as well as the reduction of the IL-1beta, IL-6, IL-8 and GM-CSF protein levels (p< 0.05). Malva sylvestris and its chloroform fraction minimized the A. actinomycetemcomitans infection and inflammation processes in oral human cells by a putative pathway that involves important cytokines and receptors. Therefore, this natural product may be considered as a successful dual anti-inflammatory-antimicrobial candidate.

Subgingival Plaque in Periodontal Health Antagonizes at Toll-Like Receptor 4 and Inhibits E-Selectin Expression on Endothelial Cells

The ability of the subgingival microbial community to induce an inappropriate inflammatory response ultimately results in the destruction of bone and gingival tissue. In this study, subgingival plaque samples from both healthy and diseased sites in the same individual were obtained from adults with chronic periodontitis and screened for their ability to either activate Toll-like receptor 2 (TLR2) or TLR4 and to antagonize TLR4-specific activation by agonist, Fusobacterium nucleatum LPS. Subgingival plaque from diseased sites strongly activated TLR4, whereas matched plaque samples obtained from healthy sites were significantly more variable, with some samples displaying strong TLR4 antagonism, while others were strong TLR4 agonists when combined with F. nucleatum LPS. Similar results were observed when TLR4 dependent E-selectin expression by endothelial cells was determined. These results are the first to demonstrate TLR4 antagonism from human plaque samples and demonstrate that healthy but not diseased sites display a wide variation in TLR4 agonist and antagonist behavior. The results have identified a novel characteristic of clinically healthy sites and warrant further study on the contribution of TLR4 antagonism in the progression of a healthy periodontal site to a diseased one.

Microbial protection and virulence in periodontal tissue as a function of polymicrobial communities: symbiosis and dysbiosis

This review discusses polymicrobial interactions with the host in both health and disease. As our ability to identify specific bacterial clonal types, with respect to their abundance and location in the oral biofilm, improves, we will learn more concerning their contribution to both oral health and disease. Recent studies examining host- bacteria interactions have revealed that commensal bacteria not only protect the host simply by niche occupation, but that bacterial interactions with host tissue can promote the development of proper tissue structure and function. These data indicate that our host-associated polymicrobial communities, such as those found in the oral cavity, co-evolved with us and have become an integral part of who we are. Understanding the microbial community factors that underpin the associations with host tissue that contribute to periodontal health may also reveal how dysbiotic periodontopathic oral communities disrupt normal periodontal tissue functions in disease. A disruption of the oral microbial community creates dysbiosis, either by overgrowth of specific or nonspecific microorganisms or by changes in the local host response where the community can now support a disease state. Dysbiosis provides the link between systemic changes (e.g. diabetes) and exogenous risk factors (e.g. smoking), and the dysbiotic community, and can drive the destruction of periodontal tissue. Many other risk factors associated with periodontal disease, such as stress, aging and genetics, are also likely to affect the microbial community, and more research is needed, utilizing sophisticated bacterial taxonomic techniques, to elucidate these effects on the microbiome and to develop strategies to target the dysbiotic mechanisms and improve periodontal health.

Antibacterial properties of a self-cured acrylic resin composed of a polymer coated with a silver-containing organic composite antibacterial agent

A novel antibacterial polymer, coated with a silver-containing organic composite antibacterial agent, was dispersed in a self-cured acrylic resin. Residual viable cell count of each oral bacterial and fungal species cultivated on acrylic resin specimens containing the antibacterial polymer was significantly decreased when compared to those cultivated on specimens prepared from untreated polymer. A strong inverse correlation was found between the amount of eluted silver ions and the residual viable cell count of all species grown on the antibacterial polymer: the lower the viable cell count, the higher the amount of eluted silver ions. This clearly indicated the antibacterial activity of silver ions. As the content of organic composite antibacterial agent added to the polymer increased from 0.5% to 1.5% in 0.5% increments, amount of eluted silver ions significantly increased with each 0.5% increment to exert greater antibacterial effect.

Hypoxia augments lipopolysaccharide-induced cytokine expression in periodontal ligament cells

Periodontitis is a chronic inflammatory disease characterized by the destruction of tooth supporting tissues. Hypoxia, the mainly changes of the plateau environment, can induce severe periodontitis by animal experiments. There is, however, very little information on hypoxia and lipopolysaccharide (LPS) induced cytokine expression in periodontal ligament (PDL) cells. In this article, we characterized hypoxia or P. gingivalis lipopolysaccharide (Pg LPS) induced tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, and IL-6 expression by human periodontal ligament (hPDL) cells. We found that hypoxia augmented Pg LPS induced TNF-α, IL-1β, and IL-6 expression in hPDL cells. We also demonstrated that nuclear factor kappa B pathway was involved in hypoxia augmenting Pg LPS induced cytokine expression in hPDL cells. Thus, our results suggest that the hypoxic environment may enhance the immune function of hPDL cells that is induced by Pg LPS.

Association of Periodontal Disease and Pre-term Low Birth Weight Infants

The incidence of pre-term low birth weight still prevails in developed as well as developing countries though the numbers may vary. Periodontitis is a chronic inflammatory process with multifactorial etiology and adversely affects the outcome of pregnancy which becomes a major public health problem. The association of periodontitis as risk factor for pre-term birth has been in extensive research in the past two decades when a number of studies investigated this relationship. However, definite connection has not been proved yet and research is still ongoing. This article describes about the possible relationship that can exist between pre-term low birth weight infants and periodontal disease.

Attenuation of Porphyromonas gingivalis oral infection by α-amylase and pentamidine

The Porphyromonas gingivalis bacterium is one of the most influential pathogens in oral infections. In the current study, the antimicrobial activity of α-amylase and pentamidine against Porphyromonas gingivalis was evaluated. Their in vitro inhibitory activity was investigated with the agar overlay technique, and the minimal inhibitory and bactericidal concentrations were determined. Using the bactericidal concentration, the antimicrobial actions of the inhibitors were investigated. In the present study, multiple techniques were utilized, including scanning electron microscopy (SEM), general structural analysis and differential gene expression analysis. The results obtained from SEM and bactericidal analysis indicated a notable observation; the pentamidine and α-amylase treatment destroyed the structure of the bacterial cell membranes, which led to cell death. These results were used to further explore these inhibitors and the mechanisms by which they act. Downregulated expression levels were observed for a number of genes coding for hemagglutinins and gingipains, and various genes involved in hemin uptake, chromosome replication and energy production. However, the expression levels of genes associated with iron storage and oxidative stress were upregulated by α-amylase and pentamidine. A greater effect was noted in response to pentamidine treatment. The results of the present study demonstrate promising therapeutic potential for α-amylases and pentamidine. These molecules have the potential to be used to develop novel drugs and broaden the availability of pharmacological tools for the attenuation of oral infections caused by Porphyromonas gingivalis.

Extract from Rumex acetosa L. for prophylaxis of periodontitis: inhibition of bacterial in vitro adhesion and of gingipains of Porphyromonas gingivalis by epicatechin-3-O-(4β→8)-epicatechin-3-O-gallate (procyanidin-B2-Di-gallate)

BACKGROUND

The aerial parts of Rumex acetosa L. have been used in traditional European medicine for inflammatory diseases of the mouth epithelial tissue. The following study aimed to investigate the influence of a proanthocyanidin-enriched extract from R. acetosa extract against the adhesion of Porphyromonas gingivalis (P. gingivalis), a pathogen strongly involved in chronic and aggressive periodontitis. A further goal was to define the bioactive lead structures responsible for a potential antiadhesive activity and to characterize the underlying molecular mechanisms of the antiadhesive effects.

METHODOLOGY

An extract of R. acetosa (RA1) with a defined mixture of flavan-3-ols, oligomeric proanthocyanidins and flavonoids, was used. Its impact on P. gingivalis adhesion to KB cells was studied by flow cytometry, confocal laser scanning microscopy and in situ adhesion assay using murine buccal tissue. RA1 and its compounds 1 to 15 were further investigated for additional effects on gingipain activity, hemagglutination and gene expression by RT-PCR.

PRINCIPAL FINDINGS

RA1 (5 to 15 μg/mL) reduced P. gingivalis adhesion in a dose-dependent manner to about 90%. Galloylated proanthocyanidins were confirmed to be responsible for this antiadhesive effect with epicatechin-3-O-gallate-(4β,8)-epicatechin-3'-O-gallate (syn. procyanidin B2-di-gallate) being the lead compound. Ungalloylated flavan-3-ols and oligomeric proanthocyanidins were inactive. RA1 and the galloylated proanthocyanidins strongly interact with the bacterial virulence factor Arg-gingipain, while the corresponding Lys-gingipain was hardly influenced. RA1 inhibited also hemagglutination. In silico docking studies indicated that epicatechin-3-O-gallate-(4β,8)-epicatechin-3'-O-gallate interacts with the active side of Arg-gingipain and hemaglutinin from P. gingivalis; the galloylation of the molecule seems to be responsible for fixation of the ligand to the protein. In conclusion, the proanthocyanidin-enriched extract RA1 and its main active constituent procyanidin B2-di-gallate protect cells from P. gingivalis infection by inhibiting bacterial adhesion to the host cell. RA1 and procyanidin B2-di-gallate appear to be promising candidates for future cytoprotective preparations for oral mouth care products.

Lineage variability in surface components expression within Porphyromonas gingivalis

The periodontopathogen Porphyromonas gingivalis is represented by a spectrum of phenotypes ranging from commensals to pathogenic lineages. Capsule and fimbriae are considered key virulence factors in this specie, involved in colonization and host defenses evasion. Since these virulence traits may not be expressed by certain strains, we aimed to test the hypothesis that certain clusters or genotypes of P. gingivalis correlate with the production of capsule and fimbriae. Sixteen P. gingivalis isolates were evaluated. Capsule (K) was detected by optical microscopy of negatively stained cells. The presence of fimbriae (F) was determined by TEM. Genotypes were determined by NotI macrorestriction fragments analysis through Pulsed-Field Gel Electrophoresis (PFGE) and Multi-locus sequence typing (MLST) based on seven house-keeping genes. The phenotypes included F(+)K(+) (n = 4), F(-)K(+) (n = 5), F(+)K(-) (n = 5) and F(-)K(-) (n = 2). The analysis of whole genome macrorestriction fragments revealed 14 different clusters. MLST data also revealed extensive genetic diversity; however, PFGE and MLST profiles showed evident differences. There was no association between P. gingivalis clusters and encapsulated and/or fimbriated phenotypes. Genotyping methods were not able to discriminate isolates according to the production of virulence factors such as capsule and major fimbriae, indicating that recombination played a key role in the expression of capsule and fimbriae in P. gingivalis.